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https://github.com/linux-apfs/linux-apfs-rw.git
synced 2026-08-18 02:19:59 -07:00
Use the common dstream code to read dstream xattrs
Before we actually implement creation and deletion of dstream xattrs, first convert the existing (read-only) functionality to use the common code provided by the last patch. The code is a little hacky in that it uses temporary buffer heads that are immediately discarded. It could be done better, but I don't want to put much effort into it because I plan to get rid of buffer heads soon. Signed-off-by: Ernesto A. Fernández <ernesto@corellium.com>
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Ernesto A. Fernández committed
1 parent
c550a8529c
commit
9b71ea9b0f
1 file changed
+67
-72
@@ -56,6 +56,26 @@ static int apfs_xattr_from_query(struct apfs_query *query,
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return 0;
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}
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/**
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* apfs_dstream_from_xattr - Get the dstream info for a dstream xattr
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* @sb: filesystem superblock
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* @xattr: in-memory xattr record (already sanity-checked)
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* @dstream: on return, the data stream info
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*/
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static void apfs_dstream_from_xattr(struct super_block *sb, struct apfs_xattr *xattr, struct apfs_dstream_info *dstream)
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{
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struct apfs_xattr_dstream *xdata = (void *)xattr->xdata;
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dstream->ds_sb = sb;
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dstream->ds_id = le64_to_cpu(xdata->xattr_obj_id);
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dstream->ds_size = le64_to_cpu(xdata->dstream.size);
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dstream->ds_sparse_bytes = 0; /* Irrelevant for xattrs */
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dstream->ds_cached_ext.len = 0;
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dstream->ds_ext_dirty = false;
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spin_lock_init(&dstream->ds_ext_lock);
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}
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/**
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* apfs_xattr_extents_read - Read the value of a xattr from its extents
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* @parent: inode the attribute belongs to
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@@ -75,94 +95,69 @@ static int apfs_xattr_extents_read(struct inode *parent,
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void *buffer, size_t size, bool only_whole)
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{
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struct super_block *sb = parent->i_sb;
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struct apfs_sb_info *sbi = APFS_SB(sb);
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struct apfs_key key;
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struct apfs_query *query;
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struct apfs_xattr_dstream *xdata;
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u64 extent_id;
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int length;
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struct apfs_dstream_info *dstream;
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int length, blkcnt, i;
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int ret;
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int i;
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xdata = (struct apfs_xattr_dstream *) xattr->xdata;
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length = le64_to_cpu(xdata->dstream.size);
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if (length < 0 || length < le64_to_cpu(xdata->dstream.size))
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return -E2BIG;
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dstream = kzalloc(sizeof(*dstream), GFP_KERNEL);
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if (!dstream)
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return -ENOMEM;
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apfs_dstream_from_xattr(sb, xattr, dstream);
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if (dstream->ds_size > XATTR_SIZE_MAX) {
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ret = -E2BIG;
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goto out;
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}
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length = dstream->ds_size;
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if (!buffer) {
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/* All we want is the length */
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ret = length;
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goto out;
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}
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if (!buffer) /* All we want is the length */
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return length;
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if (only_whole) {
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if (length > size) /* xattr won't fit in the buffer */
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return -ERANGE;
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if (length > size) {
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/* xattr won't fit in the buffer */
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ret = -ERANGE;
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goto out;
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}
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} else {
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if (length > size)
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length = size;
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}
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extent_id = le64_to_cpu(xdata->xattr_obj_id);
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/* We will read all the extents, starting with the last one */
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apfs_init_file_extent_key(extent_id, 0 /* offset */, &key);
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blkcnt = (length + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
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for (i = 0; i < blkcnt; i++) {
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struct buffer_head tmp; /* XXX */
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struct buffer_head *bh;
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int off, tocopy;
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query = apfs_alloc_query(sbi->s_cat_root, NULL /* parent */);
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if (!query)
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return -ENOMEM;
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query->key = &key;
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query->flags = APFS_QUERY_CAT | APFS_QUERY_MULTIPLE | APFS_QUERY_EXACT;
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/*
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* The logic in this loop would allow a crafted filesystem with a large
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* number of redundant extents to become stuck for a long time. We use
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* the xattr length to put a limit on the number of iterations.
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*/
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ret = -EFSCORRUPTED;
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for (i = 0; i < (length >> parent->i_blkbits) + 2; i++) {
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struct apfs_file_extent ext;
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u64 block_count, file_off;
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int err;
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int j;
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err = apfs_btree_query(sb, &query);
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if (err == -ENODATA) { /* No more records to search */
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ret = length;
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goto done;
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}
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if (err) {
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ret = err;
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goto done;
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tmp.b_blocknr = -1;
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ret = __apfs_get_block(dstream, i, &tmp, false /* create */);
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if (ret)
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goto out;
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if (tmp.b_blocknr == -1) {
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/* No holes in xattr dstreams, I believe */
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ret = -EFSCORRUPTED;
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goto out;
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}
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err = apfs_extent_from_query(query, &ext);
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if (err) {
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apfs_alert(sb, "bad extent for xattr in inode 0x%llx",
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apfs_ino(parent));
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ret = err;
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goto done;
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bh = apfs_sb_bread(sb, tmp.b_blocknr);
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if (!bh) {
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ret = -EIO;
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goto out;
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}
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block_count = ext.len >> sb->s_blocksize_bits;
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file_off = ext.logical_addr;
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for (j = 0; j < block_count; ++j) {
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struct buffer_head *bh;
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int bytes;
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if (length <= file_off) /* Read the whole extent */
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break;
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bytes = min(sb->s_blocksize,
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(unsigned long)(length - file_off));
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bh = apfs_sb_bread(sb, ext.phys_block_num + j);
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if (!bh) {
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ret = -EIO;
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goto done;
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}
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memcpy(buffer + file_off, bh->b_data, bytes);
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brelse(bh);
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file_off = file_off + bytes;
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}
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off = i << sb->s_blocksize_bits;
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tocopy = min(sb->s_blocksize, (unsigned long)(length - off));
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memcpy(buffer + off, bh->b_data, tocopy);
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brelse(bh);
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}
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ret = length;
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done:
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apfs_free_query(sb, query);
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out:
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kfree(dstream);
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return ret;
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}
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